Recently, as packaging materials, for the reasons of the strength, the ability to protect products, aptitude for working environment, advertising effects by printing thereon, etc., complex flexible films obtained by combining different types of polymer materials have been mainly used. Such complex films generally have a thermoplastic film layer as an outer layer which plays a role of product protection, and a thermoplastic film layer as a sealant layer. For bonding these layers, a dry lamination method, in which an adhesive is applied to a laminated film layer to bond a sealant layer thereto, or an extrusion lamination method, in which an anchor coating agent is applied to a laminated film layer according to need and a melted plastic film to be a sealant layer is bonded thereto under pressure to provide film-like lamination, is employed. As the adhesive to be used in these methods, in general, a two-liquid type polyurethane-based adhesive consisting of a main ingredient having an active hydrogen group such as a hydroxyl group and a curing agent having an isocyanate group is mainly used because of high adhesive performance thereof (for example, see Patent Document 1 and Patent Document 2).
Further, recently, packaging materials to be used in the field of packaging of foods, pharmaceutical products, electronic precision components, etc. are required to have gas barrier properties for blocking gas, because influence of oxygen which permeates the packaging materials must be prevented in order to prevent deterioration of contents. In particular, in the case of foods, in order to suppress oxidation of oils and fats, deterioration of proteins, etc. to keep taste and freshness, in the case of pharmaceutical products, in order to suppress deterioration of an active ingredient to maintain efficacy, and in the case of electronic precision components, in order to suppress corrosion of metal parts to prevent insulation failure, packaging materials are required to have gas barrier properties.
For these reasons, various gas barrier layers such as an inorganic vapor deposition film obtained by deposition of aluminium foil, alumina (Al2O3), silica (SiO2) or the like, a polyvinylidene chloride (PVDC)-coated layer and a polyvinyl alcohol (PVA)-coated layer have been generally used.
Meanwhile, as a method for obtaining an excellent film in a short time without carrying out the heat treatment at a high temperature, use of an active-energy-ray-curable resin is mentioned. Curing of the active-energy-ray-curable resin is instantly progressed by ultraviolet irradiation to form a cured product. Therefore, high-temperature or long-time curing, which is required for curing general thermosetting resins, is not required. For this reason, the active-energy-ray-curable resin has been studied recently for the development of a wide range of applications including adhesives, printing inks and coating materials for parts which are easily damaged by heat. However, almost no active-energy-ray-curable resin having gas barrier properties is known. For example, a method of using a solution of a polyvalent metal salt of an unsaturated carboxylic acid compound is known (see Patent Document 3).